Balanced vibrating screen structure



March 14, 193 G. A. OVERSTROM 2,150,242

BALANCED VTBRATTNG SCREEN STRUCTURE Filed Dec. 20, 1935 HINVL'NTOR. flew/1m,

7 W ATTORNE s.

Patented Mar. 14, 1939 Gustave A. Overstrom, Big Sm, Calif.

' Application December 20, 1935, Serial No. 55,351

2 Claims.

This invention relates to balanced vibratin screen structures, of the type shown in my Patent No. 1,995,435, granted March 26, 1935, wherein the structure is statically and dynamically balanced at all angles of inclination of the screen element, and at all speeds of operation.

In said patent I have described and claimed a screen structure consisting of a suitableframee work upon which is resiliently mounted a screen box, balanced about its center of gravity, andhaving operating means to impart vibratory movements thereto. The resilient mounting, of the screen box is shown in said patent as consisting of spring supports disposed at the respec-' tive ends of the box, and the vibrating means are shown as being disposed substantially in alignment with the axis of balance of the screen, that is, in alignment with a line passing through the center of gravity and transversely across and 29 parallel with the surface of the screen. This 7 line I shall call the axis of balance of the screen.

The axes of the yielding supports for the respective ends of the screen box, are disposed at respectively opposite sides of, at equal distances from,

and parallel with said axis of balance, and-also with each other.

I have found that in the practical use of a balanced screen structure of this type for certain kinds of work, such, for example, as screening slaughter house and similar material, it is desirable to provide ,means to relatively vary the resilient action exerted upon the screen box by its spring supports, in order to be able to vary not only the relation of the components of the screening and feeding forces but also the direction of application of said forces upon the material under treatment. It is therefore an ob- J'ect of my present invention to provide a balanced screen structure in which the material 40 screening and feeding forces may be easily and readily varied, relatively to each other, not only in amplitude but also in direction of application. a

Other objects of the invention will appear more 5 fully hereinafter.

The invention consists substantially in the construction, combination, location, relative arrangement of parts, and mode of operation,.all as will be more fully hereinafter set forth, as

50 shown in the accompanying drawing, and finally pointed out in the appended claims.

In the accompanyin drawing,

Fig. 1 is a view in top plan of a balanced screen structure embodying the principles of my inven- 56 tion.

Figs. 2 and 3 are views respectively in side and end elevation of the same.

Fig. 4 is a broken view in side elevation of a slightly modified arrangement.

In the drawing I haveshown a framework 5 including side members or sills 5, upon which is mounted a screen box 6 in which is carried one or more screen elements I in the usual well known manner. The screen box 6 is supported in more or less inclined position upon the framework by 10 .means of resilient or yielding supports disposed at the respective ends of the screen box. These resilient supports may be ofvarious forms and arrangements. I have shown one illustrative arrangement wherein a box or housing 8, is 15 mounted at each end of each side member or sill 5 of the supporting framework. Mounted within each housing or box 8, for rotative ad- 'justment therein, is a sleeve or collar 9, each of which carries a spring support, shown in this go instance as consisting of three coil springs III, l1, l2, disposed in equally annular spaced apart relation to each other, that is, in delta arrangement, and in radial relation withrespect to the collar or sleeve which'carries-them. Each spring 25 coil bears at its outer end against the inner wall of the collar and at its inner end against a block l3, which is substantially centrally disposed within the carrier collar or sleeve 9, and which is sleeved upon a suitable projection l4 from the 30 screen box. One convenient arrangement is shown, to which, however, I do not desire to be limited or restricted, wherein a shaft I5 extends transversely across the screen box adjacent to andparallel with each end of the said box, said shafts being carried in boxes IS, on the side sills of the screen box. The ends of these shafts l5, extend beyond the sides of the screen box and receive thereon the blocks l3 against which the tension of the springs l0, ,and I2 is exerted.

In accordance with my present invention the three springs of each set constituting a yielding support for the screen box are of relatively difierent tension so as to-exert a different degree of yielding tension or resistance upon the screen box under the vibratory movements imparted to the box, and since said springs of each set are angularly displaced with relation to each other I se-. cure a resultant movement of the screen box of relatively different amplitude in relatively differ- 5 ent directions. This resultant movement can be varied by angularly or annularly adjusting as a whole the sets of supporting springs. This adjustment may be effected by angularly or annularly adjusting the blocks ll. Such adiustment of the block I3 carries with it the associated set of springs I0, I I, I2, and the enclosing collar or sleeve 9, therefor. In order to avoid irregularities in the movements of the screen box, it is important that the two spring support structures at the opposite sides of the same end of the screen box be adjusted to substantially the same extent. This is a result which can be attained in various ways. In order to avoid reliance upon unskilled labor to effect the adjustments referred to, and to ensure a coincident and corresponding adjustment of both sets of screen box spring supports at the same end of said box, the blocks I3 may be rigidly fastened on the projections I4, or, where the transverse shafts I5 are employed, upon the projecting ends of said shaft, and then rotatively moving said shaft.

The vibratory movements may be imparted to the screen box by any suitable or desired vibrating means applied in any suitable or desirable manner. I have shown a vibrating means of the unbalanced pulley type which I have found most effective and desirable for the purpose. In the form shown, a shaft I1 is mounted upon to extend transversely across the screen box, and on the said shaft is mounted the unbalanced pulley I8. I have shown an unbalanced pulley I8 mounted upon each end of said shaft. This secures a most desirable consistently uniform and steady movement of the screen box. Of course this arrangement may be varied in various well known ways at present in use. The shaft I'I may be rotated in any convenient manner and from any desired source. I have shown a simple arrangement whereby said shaft carries a drive pulley I9 at each end thereof, and at 20 I have shown a power pulley suitably geared to drive one or the other of said pulleys I9 on the shaft I'I according to the conditions of available space for erection of the structure.

It will be observed that the axes of the spring supports at the respective ends of the screen box, and of the unbalanced vibrating pulley or pulleys are not only parallel to each other but they also lie in substantially the same horizontal plane.

This secures the static and dynamic balance of the screen box.

In Fig. 4 I have shown a slightly modified arrangement wherein the screen box is mounted in a more sharply inclined position, .and the direction of rotation of the unbalanced pulley is the reverse of that of the arrangement shown in Fig. 2. By this arrangement of Fig, 4 certain particles of the material to be treated are caused to travel up the inclined surface of the screen instead of down said surface. This is desirable in screening certain kinds of materials. With this arrangement one portion of the material is delivered over the lower end of the screen element into a delivery chute 2|, while another portion is delivered through a delivery chute 22 located directly below the screen element, and a third portion is delivered over the upper end of the box into a chute 23. -However, the samefeatures of relatively difierent tensions of members of the sets of screen'box supporting springs, and of annular adjustments of said sets. of springs, and of the static and dynamic balance of the screen box, are incorporated.

From the foregoing description it will be seen that I provide a very simple structure of balanced screen, wherein and whereby under the combined, conjoint and cooperating actions of the screen box spring supports and vibrating means,forces are imparted to the screen box which cause movements of the screen element in both screening and material feeding direction, and with screening and feeding components or amplitudes, which may be varied by employing the supporting springs in sets in which the members of each set are of relatively different tensions, and in which thesets are annularly adjustable.

In Fig. 2 I have indicated diagrammatically by graphs 25, the actual movements of the screen element in operation with one particularly relative arrangement of the springs of each set and one particular relative annular adjustment of the various sets. 1

Inspection of these graphs discloses that for a complete rotation of the unbalanced pulley the upper portion of the movement is more prolonged than the lower portion, although both of said movements are eifected in the same length of time. This movement may properly be called the diiferential movement. It will also be seen that the line or direction of the differential move- This also is true of the graphs 26, of Fig. 4

with the additional variation due to the reverse direction of rotation of the unbalanced pulley.

Having now set forth the object and nature of my invention and structures embodying the principles thereof, I Wish it to be understood that my invention is not to be limited or restricted to the exact details of structure and arrangement shown and described. But what I claim as new and useful, and of my own invention, and desire to secure by Letters Patent is,

1. In a screen structure the combination comprising a screen box, a pair ofshafts mounted on the box and extending transversely thereof near each end so as to project beyond the sides thereof, a supporting base, spring housings mounted on the base adjacent the projecting ends of the shafts, and a plurality of radially aligned springs mounted in each of the housings and engaging the shaft ends, the springs in each of the housings being of relatively different strengths and means mounted on the screen box In this way also the screening and for vibrating it, said shafts being angularly adjustable about their individual axes to effect simultaneous angular adjustment of the springs associated therewith at each end.

2. In a screen structure, a screen box having supporting members, supporting springs disposed within collars in radial relation to said members to support the same, said springs having relatively different resistances to deflection, and housings enclosing said collars, said collars and said housings having cooperating circular bearing surfaces and being so constructed and arranged that the collars may be rotated within the housings, thereby angularly adjusting the collars and their associated springs about the axes of said supporting members.

GUSTAVE A. OVERS'I'ROM. 

